Just to see if I could print something highly interlinked in one go, I created a Ring Mail design in OpenSCAD for fun.

[Now with Customizer support.]

This is a hard item to print. All the little parts will want to pop off of the board, due to low surface area. You may need to use a raft, or brim, or a print-bed surface preparation like a PVA glue wash to get the parts to stick tightly.

If you need to tweak the sizes for this design:

1. Unpack the .zip file.
2. Edit the .scad file to tweak the parameters.
3. Open the .scad file with OpenSCAD.
4. Select Render from the Design menu.
5. Select "Export as STL..." from the File->Export menu.
6. Save the STL file.
7. Slice the STL file.
8. Print.